Plot and cast details are being kept under wraps. However, it has been confirmed that Robert Downey Jr., Chris Pratt, Chris Evans, Chris Hemsworth and Elizabeth Olsen are set to star in Avengers: Infinity War, which the Russos will direct from a screenplay written by Captain America writers Christopher Markus and Stephen McFeely.

The Infinity War title comes from a classic 1992 comic book series in which the heroes of the Marvel Universe are brought together to fight sinister doppelgangers of themselves. The evil doppelgangers are created by a cosmic entity called the Magus, the evil side of Adam Warlock who wants control of the Infinity Gauntlet.

Avengers: Infinity War is set to be released in US theatres on May 4, 2018, while the fourth instalment of the film series will come out on May 3, 2019.